Number of Irreflexive Relations on a Set | C # program for above approach ; Function to calculate x ^ y modulo 1000000007 in O ( log y ) ; Stores the result of x ^ y ; Update x if it exceeds mod ; If x is divisible by mod ; If y is odd , then multiply x with result ; Divide y by 2 ; Update the value of x ; Return the resultant value of x ^ y ; Function to count the number of irreflixive relations in a set consisting of N elements ; Return the resultant count ; Driver code
using System ; public class GFG { static int mod = 1000000007 ; static int power ( int x , int y ) { int res = 1 ; x = x % mod ; if ( x == 0 ) return 0 ; while ( y > 0 ) { if ( ( y & 1 ) != 0 ) res = ( res * x ) % mod ; y = y >> 1 ; x = ( x * x ) % mod ; } return res ; } static int irreflexiveRelation ( int N ) { return power ( 2 , N * N - N ) ; } public static void Main ( String [ ] args ) { int N = 2 ; Console . WriteLine ( irreflexiveRelation ( N ) ) ; } }